scholarly journals Scanning electron microscope evaluation of the marginal gap and internal fit of additive versus subtractive fabrication techniques for posterior lithium disilicate crowns

2019 ◽  
Vol 65 (3) ◽  
pp. 2779-2793
Author(s):  
Marwa Beleidy ◽  
Ahmed Ziada
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Lithium Disilicate ◽  
Marginal Gap ◽  
Internal Fit ◽  
Scanning Electron

scholarly journals Scanning electron microscope comparative surface evaluation of glazed-lithium disilicate ceramics under different irradiation settings of Nd:YAG and Er:YAG lasers

2017 ◽  
Vol 88 (1) ◽  
pp. 75-81 ◽  
Author(s):  
Josko Viskic ◽  
Drazen Jokic ◽  
Suzana Jakovljevic ◽  
Lana Bergman ◽  
Sladana Milardovic Ortolan ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Laser Energy ◽  
Lithium Disilicate ◽  
Surface Roughening ◽  
Dental Ceramics ◽  
Treated Sample ◽  
Power Setting ◽  
Dental Lasers ◽  
Scanning Electron

ABSTRACT Objective: To evaluate the surface of glazed lithium disilicate dental ceramics after irradiation under different irradiation settings of Nd:YAG and Er:YAG lasers using a scanning electron microscope (SEM). Materials and Methods: Three glazed-press lithium disilicate ceramic discs were treated with HF, Er:YAG, and Nd:YAG, respectively. The laser-setting variables tested were laser mode, repetition rate (Hz), power (W), time of exposure (seconds), and laser energy (mJ). Sixteen different variable settings were tested for each laser type, and all the samples were analyzed by SEM at 500× and 1000× magnification. Results: Surface analysis of the HF-treated sample showed a typical surface texture with a homogenously rough pattern and exposed ceramic crystals. Er:YAG showed no effect on the surface under any irradiation setting. The surface of Nd:YAG-irradiated samples showed cracking, melting, and resolidifying of the ceramic glaze. These changes became more pronounced as the power increased. At the highest power setting (2.25 W), craters on the surface with large areas of melted or resolidified glaze surrounded by globules were visible. However, there was little to no exposure of ceramic crystals or visible regular surface roughening. Conclusions: Neither Er:YAG nor Nd:YAG dental lasers exhibited adequate surface modification for bonding of orthodontic brackets on glazed lithium disilicate ceramics compared with the control treated with 9.5% HF.

scholarly journals Margınal ıntegrıty of fıve dıfferent root sealers ın retrograde fıllıng followıng apıcoectomy: An ın vıtro analysıs wıth scannıng electron mıcroscope and mıcro-radıography

2019 ◽  
Author(s):  
Yahya Acil ◽  
Pinar Kiymet Karataban ◽  
Aydin Gülses ◽  
Mustafa Ayna ◽  
Jörg Wiltfang
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Root Canal ◽  
Marginal Gap ◽  
Filling Materials ◽  
Retrograde Filling ◽  
Ah Plus ◽  
Root Canal Sealers ◽  
Scanning Electron

Abstract Objective The aim was to clarify the physical properties of five different root canal sealers used as retrograde filling materials on the resected root apex following apicoectomies.Materials and Methods Apical resection was performed on 100 canals of 50 maxillary premolars in slaughtered pigs. The root end of 24 canals were retrogradely filled with Diaket ™, 37 root canals with Super-EBA ™ including 18 with Super-EBA ™ Regular and 19 with Super-EBA ™ fast, 20 canals with ProRoot® MTA and 19 canals with AH-Plus ™. For quantitative examination, scanning electron microscope (SEM) analysis and for qualitative examination microradiography was performed.Results Diaket ™ achieved the best results with an overall average of 4.872 microns gap value. The mean values of marginal gap widths of AH - Plus ™ and Super - EBA ™ were almost the same magnitude 8.044 microns and 9.951 microns respectively, followed by Super - EBA ™ Regular with 11,560 microns. Highest marginal gap value was detected in ProRoot® MTA with 18.343 microns (p < 0.001) .Conclusion According to the limited knowledge of the current in vitro study Diaket ™ achieved the best results compared to the other materials. Additional clinical studies with long term follow up period might help to determine the most appropriate root-end filling material.Clinical Relevance Among five different root canal sealers used as retrograde filling materials, in terms of its marginal integrity and material properties, Diaket ™ can be referred as the most suitable material for retrograde obturation.

The Alteration of the Pore Spaces in Sandstones

1973 ◽  
Vol 31 ◽  
pp. 210-211
Author(s):  
R. E. Ferrell ◽  
G. G. Paulson
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
The Other ◽  
Coarse Grained ◽  
Depositional Fabric ◽  
Soluble Components ◽  
Scanning Electron ◽  
Shape And Size

The pore spaces in sandstones are the result of the original depositional fabric and the degree of post-depositional alteration that the rock has experienced. The largest pore volumes are present in coarse-grained, well-sorted materials with high sphericity. The chief mechanisms which alter the shape and size of the pores are precipitation of cementing agents and the dissolution of soluble components. Each process may operate alone or in combination with the other, or there may be several generations of cementation and solution.The scanning electron microscope has ‘been used in this study to reveal the morphology of the pore spaces in a variety of moderate porosity, orthoquartzites.

The Broad Applications of the Scanning Electron Microscope

1969 ◽  
Vol 27 ◽  
pp. 20-21
Author(s):  
C. T. Nightingale ◽  
S. E. Summers ◽  
T. P. Turnbull
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Light Microscopy ◽  
Surface Topography ◽  
Great Depth ◽  
Resolving Power ◽  
Depth Of Field ◽  
Pictorial Representations ◽  
Scanning Electron

The ease of operation of the scanning electron microscope has insured its wide application in medicine and industry. The micrographs are pictorial representations of surface topography obtained directly from the specimen. The need to replicate is eliminated. The great depth of field and the high resolving power provide far more information than light microscopy.

Observability of Very Thick Specimen by Using Transmission Scanning Electron Microscope

1971 ◽  
Vol 29 ◽  
pp. 26-27
Author(s):  
K. Shibatomi ◽  
T. Yamanoto ◽  
H. Koike
Keyword(s):  
Electron Microscope ◽  
Image Quality ◽  
Scanning Electron Microscope ◽  
Chromatic Aberration ◽  
Image Contrast ◽  
Objective Lens ◽  
Thick Specimen ◽  
Transmission Electron ◽  
Scanning Electron

In the observation of a thick specimen by means of a transmission electron microscope, the intensity of electrons passing through the objective lens aperture is greatly reduced. So that the image is almost invisible. In addition to this fact, it have been reported that a chromatic aberration causes the deterioration of the image contrast rather than that of the resolution. The scanning electron microscope is, however, capable of electrically amplifying the signal of the decreasing intensity, and also free from a chromatic aberration so that the deterioration of the image contrast due to the aberration can be prevented. The electrical improvement of the image quality can be carried out by using the fascionating features of the SEM, that is, the amplification of a weak in-put signal forming the image and the descriminating action of the heigh level signal of the background. This paper reports some of the experimental results about the thickness dependence of the observability and quality of the image in the case of the transmission SEM.

Resolution of a Transmitted Electron Image Formed by A Scanning Electron Microscope

1970 ◽  
Vol 28 ◽  
pp. 386-387
Author(s):  
S. Takashima ◽  
H. Hashimoto ◽  
S. Kimoto
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Chromatic Aberration ◽  
Objective Lens ◽  
Specimen Thickness ◽  
Probe Diameter ◽  
Transmission Electron ◽  
Electron Image ◽  
Conventional Transmission Electron Microscope ◽  
Scanning Electron

The resolution of a conventional transmission electron microscope (TEM) deteriorates as the specimen thickness increases, because chromatic aberration of the objective lens is caused by the energy loss of electrons). In the case of a scanning electron microscope (SEM), chromatic aberration does not exist as the restrictive factor for the resolution of the transmitted electron image, for the SEM has no imageforming lens. It is not sure, however, that the equal resolution to the probe diameter can be obtained in the case of a thick specimen. To study the relation between the specimen thickness and the resolution of the trans-mitted electron image obtained by the SEM, the following experiment was carried out.

Characterization of Sputtered Films using the Scanning Electron Microscope

1973 ◽  
Vol 31 ◽  
pp. 44-45
Author(s):  
R. F. Schneidmiller ◽  
W. F. Thrower ◽  
C. Ang
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
Sputtered Films ◽  
Plasma Sputtering ◽  
Microelectronic Devices ◽  
Control Film ◽  
Scanning Electron

Solid state materials in the form of thin films have found increasing structural and electronic applications. Among the multitude of thin film deposition techniques, the radio frequency induced plasma sputtering has gained considerable utilization in recent years through advances in equipment design and process improvement, as well as the discovery of the versatility of the process to control film properties. In our laboratory we have used the scanning electron microscope extensively in the direct and indirect characterization of sputtered films for correlation with their physical and electrical properties.Scanning electron microscopy is a powerful tool for the examination of surfaces of solids and for the failure analysis of structural components and microelectronic devices.

Field Emission SEM Equipped With Noise Compensator

1973 ◽  
Vol 31 ◽  
pp. 302-303
Author(s):  
S. Saito ◽  
H. Todokoro ◽  
S. Nomura ◽  
T. Komoda
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Scanning Electron Microscope ◽  
Field Emission ◽  
Low Contrast ◽  
Probe Current ◽  
High Resolution Images ◽  
Scanning Electron

Field emission scanning electron microscope (FESEM) features extremely high resolution images, and offers many valuable information. But, for a specimen which gives low contrast images, lateral stripes appear in images. These stripes are resulted from signal fluctuations caused by probe current noises. In order to obtain good images without stripes, the fluctuations should be less than 1%, especially for low contrast images. For this purpose, the authors realized a noise compensator, and applied this to the FESEM.Fig. 1 shows an outline of FESEM equipped with a noise compensator. Two apertures are provided gust under the field emission gun.

Visualization of Internal Skin Structures with the Scanning Electron Microscope

1969 ◽  
Vol 27 ◽  
pp. 46-47
Author(s):  
Emil Bernstein
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Great Depth ◽  
Hair Follicles ◽  
Depth Of Field ◽  
Pig Skin ◽  
Realistic Picture ◽  
Main Components ◽  
Scanning Electron

An interesting method for examining structures in g. pig skin has been developed. By modifying an existing technique for splitting skin into its two main components—epidermis and dermis—we can in effect create new surfaces which can be examined with the scanning electron microscope (SEM). Although this method is not offered as a complete substitute for sectioning, it provides the investigator with a means for examining certain structures such as hair follicles and glands intact. The great depth of field of the SEM complements the technique so that a very “realistic” picture of the organ is obtained.

Fine structure of the retina of the giant scallop, Placopecten magellanicus

1984 ◽  
Vol 42 ◽  
pp. 312-313
Author(s):  
C.V.L. Powell
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Light Intensity ◽  
Scanning Electron Microscope ◽  
Eye Development ◽  
Preliminary Observation ◽  
Columnar Epithelium ◽  
Placopecten Magellanicus ◽  
Environmental Light ◽  
Scanning Electron

The overall fine structure of the eye in Placopecten is similar to that of other scallops. The optic tentacle consists of an outer columnar epithelium which is modified into a pigmented iris and a cornea (Fig. 1). This capsule encloses the cellular lens, retina, reflecting argentea and the pigmented tapetum. The retina is divided into two parts (Fig. 2). The distal retina functions in the detection of movement and the proximal retina monitors environmental light intensity. The purpose of the present study is to describe the ultrastructure of the retina as a preliminary observation on eye development. This is also the first known presentation of scanning electron microscope studies of the eye of the scallop.

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